The Vatican opposes the congress, saying it breaches Catholic doctrine about bishops' autonomy.

Sino-Vatican relations were already strained after Beijing's unilateral ordination of a bishop in Hebei last month.

Brandishing slogans and wearing their white uniforms, about 100 seminarians studying for the priesthood at the Catholic Theological and Philosophical Seminary of Hebei in Shijiazhuang staged a silent protest outside the offices of the Hebei Ethnic and Religious Affairs Bureau from early yesterday morning.

They demanded that the government remove the seminary's newly appointed deputy rector.

'We have no option but to stage this silent protest,' said one seminarian who took part. 'We can stand the situation no longer.'

Bureau officials said they were negotiating with the protesters but refused to give further details.

Tang Zhaojun, a section chief at the bureau who is not a Catholic, was appointed by the government on November 11 to the seminary's leadership. He will take part in managing the religious institute and teach political education classes.

The appointment sparked an uproar among the students, who have been on strike for two weeks with the support of their teachers, demanding that government officials not be appointed to head seminaries.

Church insiders said the government had promised earlier to remove Tang in light of the strong protests by members of the seminary.

But the possible resolution was thwarted after Beijing's ordination of Joseph Guo Jincai as bishop of the Chengde diocese last month.

Some of the eight bishops who took part in what the Vatican called an 'illicit' ordination ceremony are directors of the seminary. The rector is Joseph Ma Yinglin, who was ordained without papal approval as bishop of Kunming, Yunnan , in 2006.

At two meetings with the seminarians yesterday, officials refused to remove Tang 'because the appointment was a [Communist] Party decision', some of those present said.

Anthony Lam Sui-ki, a senior researcher with Hong Kong's Holy Spirit Study Centre, said the rising discontent among Catholics against the government as demonstrated in the protest could deter bishops who are loyal to Rome from attending next week's national congress.

Yesterday's open protest by Catholic seminarians against the authorities was the first since January 2000, when more than 150 seminarians at the National Seminary in Beijing refused to attend a ceremony in which five bishops were ordained by the government without papal approval.

Many of those who took part in that boycott were dismissed from the seminary.

Additional reporting by Mandy Zuo